Idling Myths Versus Reality

Ask any motorists why they idle their vehicles, and you’ll likely get one of several simple answers: “to warm up the engine before they drive away”. “It takes more gas to restart”, and to talk on the cell phone. These are some of the most commonly held myths. These myths costs you money, wear out your vehicle’s engine and generate unnecessary greenhouse gas emissions that contribute to climate change.

Contrary to popular belief, idling is not an effective way to warm up your vehicle, even in cold weather. The best way to warm it up is to drive it. In fact, with today’s engines, you need no more than 30 seconds of idling on winter days before you start to drive.

The idea, that turning off the car, (then restarting it) uses more gas, is firmly rooted in our automotive dominate society, yet it is  pure bunk. One of the major reasons that hybrids get great gas mileage is because of instant off technology where the engine is shut off instantly when not needed. These ultra efficient cars stop the engine automatically when possible, not 3 minutes, not 10 seconds of idling, but instantly at all stop lights, and when not needed.

The notion that idling is good for your vehicle is passé – in fact, it hasn’t been the right thing to do since the advent of electronic engines. The truth is that excessive idling can damage the engine.

The reason? An idling engine isn’t operating at its peak temperature, which means that fuel doesn’t undergo complete combustion. This leaves fuel residues that can condense on cylinder walls, where they can contaminate oil and damage parts of the engine. For example, fuel residues are often deposited on spark plugs. As you spend more time idling, the average temperature of the spark plug drops. This makes the plug get dirty more quickly, which can increase fuel consumption by 4 to 5 percent. Excessive idling also lets water condense in the vehicle’s exhaust. This can lead to corrosion and reduce the life of the exhaust system.

On older cars that have weak oil pumps, there is not enough oil pressure at low RPMs to get oil to all the critical locations – this causes premature wear on the engine, and will cause more pollution, and failure of bearings, and other moving parts.

Besides, what’s often forgotten is that idling warms only the engine – not the wheel bearings, steering, suspension, transmission and tires. These parts also need to be warmed up, and the only way to do that is to drive the vehicle.

Perhaps you’re concerned that continually shutting off and restarting the vehicle is hard on the engine. But studies show that frequent restarting has little impact on engine parts such as the battery and starter motor. The wear on components that restarting the engine causes little or no wear – with a properly tuned engine. If you have a hard time starting the car GET A TUNE UP – money that you spend you’ll likely recover several times over in fuel savings from reduced idling, and better performance.

So, when should you turn off the engine? Believe it or not, more than 10 seconds of idling uses more fuel than restarting the engine. As a rule of thumb, if you’re going to stop for 10 seconds or more – except in traffic – turn the engine off. You’ll save money. And your vehicle won’t produce harmful emissions of carbon dioxide, the principal greenhouse gas that contributes to climate change.

Oh, and as far as that cell phone goes, it really works better if you shut the engine off. Pull over, shut the engine, and talk as long as you want.


News Release — Idle-Free VT
May 2, 2014

Wayne Michaud
Director, Idle-Free VT Inc.

Montpelier, Vermont, May 5, 2014 – Vermont’s prohibited idling of motor vehicles law takes effect May 5, 2014. This law applies to all motor vehicles. It limits the idling of vehicles to five minutes in any 60-minute period. A penalty of $10.00 will be assessed for a first violation; $50.00 for a second violation; $100.00 for a third and subsequent violations.

There are exceptions to the five-minute limit, including but not limited to:

• Police, fire or emergency vehicle idling
• Commercial bus idling when passengers are on board
• Idling to ensure adequate windshield defrosting
• Idling to power work-related operations for trucks
• Idling for sleeper berth purposes
• Idling for maintenance, repair, service or diagnostic purposes
• Idling on private property for vehicles of 10,000 pounds or less

To read the full law, Google: “Prohibited idling of motor vehicles” or visit:

For more information about idling laws, facts, and the significant benefits in avoiding unnecessary idling, visit